Back in 2010 I captured a widefield mosaic of the Rho Ophiuchus area that overtime became one of my "signature" deep sky images:
I captured that image with broadband filters - in plain language, I used filters that only pass the light within the rainbow colors, in other words the image shows what regular cameras usually capture.
A few days ago, checking some data and sky surveysm I noticed that in this area there were also some very clearly delimited nebulosity emitting light in the very narrow Hydrogen Alpha band that however were not showing in my original image - or in any other image of this area.
So, during the last few days I spent the last hours of the night capturing H-Alpha data in this area. I integrated this data with the previous image and voila:
The "new" emission nebulosity is most apparent, as you can see, in the left area of the image, particularly around the stars Delta Scorpii (SH2-7) and Pi Scorpii (SH2-1).
Visually, some people may argue that the previous image is more catchy, however, my intention wasn't to produce a better (or worst) image, but one that will show this "new" data that does not appear in "regular" broadband images.
Here's a Blink version of both images:
Interesting, isn't it? I've been missing all that red nebulosity all these years and nobody complained ;-)